1. Field of the Invention
The present invention relates to an ostomy appliance comprising a deodorising filter, in particular ostomy bags.
In connection with surgery for a number of diseases in the gastro-intestinal tract a consequence is, in many cases, that after a colostomy, an ileostomy or an urostomy, the patient is left with a stoma in the abdominal wall for the discharge of the effluents or waste products of the body, which are conveyed through the colon, the ileum or the ureter. The discharge of visceral contents including intestinal gases cannot be regulated at will, and for that purpose the opening may be closed with a closure means, e.g. a tampon or a magnetic closure, or the patient will have to rely on an appliance to collect the material emerging from such opening in the form of a receiving bag which is later emptied and/or discarded at suitable times.
Ostomy appliances are well known. Such appliances may be two-piece or one-piece appliances. In both types of appliances, an adhesive wafer is attached to the wearer's skin. In case of a one-piece appliance, a receiving member or bag is attached to the adhesive wafer. In case of a two-piece appliance, the adhesive wafer forms part of a body side member and a receiving bag is attached releasably to the body side ostomy member for receiving exudates from the stoma.
When using one-piece appliances, the whole appliance, including the adhesive skin barrier securing the appliance to the skin is normally removed and replaced by a fresh appliance. When using two-piece appliances, the body side member is left in place up to several days, and only the receiving bag attached to the body side member is replaced.
The discharge of flatus, measured in volume, may exceed the discharge of solid and liquid faecal matter by many hundred percent and therefore there is usually the need for the continuous or frequent venting of the intestine or the collecting bag. Normally the outflowing flatus is deodorised with a suitable filter. Commonly the active filter is powdered active carbon, which absorbs H2S being the principal component of the smell of flatus.
In connection with the use of filters there is a need of measures for effectively preventing blocking of the inlet opening of filters of ostomy appliances. When the inlet opening of the filter is blocked, the gas discharged into the ostomy appliance cause ballooning of the bag which is highly undesirable for several reasons. Ballooning will be embarrassing for the user as the bag will bulge and there is an increased risk of leakage which is unacceptable for the user.
2. Description of the Related Art
Various constructions of filters for ostomy appliances are known. In the state of the art, the filters are designed so as to obtain a high security of deodorisation of the flatus by securing that there is no by-pass by which the flatus may circumvent the filter, and some measures have been discussed with respect to obtaining a better security against blocking of the inlet of the filter by solid discharged visceral content.
Thus, European Patent No. 0 235 928 discloses that a filter may be rendered suitable for use with ileostomy equipment when the filter wall adapted to face the source of intestinal gas is covered by a layer of sheet material, preferably plastic sheet material connected to the filter walls and, inside the periphery of this connection, provided with openings such as slits for the passage of intestinal gas. However, such slits may open if the pressure is high giving free flow of gas and liquid through the layer of sheet material. As an additional or alternative measure, it is proposed to provide the filter housing on the surface adapted to face the source of intestinal gas with a layer of liquid-absorbing material.
EP patent No. 0 443 728 B1 discloses a bag for receiving discharge from the human body comprising a filter and an intervening membrane covering the inlet opening of the filter, said intervening membrane being gas permeable but not liquid permeable. It is mentioned that the membrane may comprise a polyester film bonded to a PTFE film and that such membrane showed no leakage of water. There is no indication of security against leaking when exposed for discharge from an ileostomy or liquids from a colostomy.
Published International Patent Application WO 98/44880 discloses a filter for covering a vent of an ostomy appliance, said filter comprising an elongated, substantially flat filter body of a porous filter material interposed between gas and liquid impervious walls which are sealed to the body along its longitudinal side edges; gas inlet and outlet openings being provided in communication with the filter material adjacent to its respective longitudinal end regions, wherein both of the gas and liquid impervious walls are sealed to the upper and lower surfaces of the filter body, wherein the inlet opening is covered by a hydrophobic sheet, wherein the inlet opening is covered with a microporous oleophobic membrane and wherein a foam material is covering the inlet opening of the vent. Such arrangement shows improved resistance against wetting and blocking of the filter caused by humidity or other liquid constituents of the visceral contents of an ostomy collection bag and, at the same time, shows improved resistance against clogging of the filter.
U.S. Pat. No. 4,938,750 discloses a medical device comprising a collection receptacle in the form of a thin walled pouch, a member affixed to the pouch wall comprising a plurality of isolated gas passages, each constituting a vent, separate deodorising filter means in each one of said passages and means for obstructing the flow through all but a selected one of said passages. The passages and the filter means are located on a member which is preferably aligned with the stoma receiving opening. With this location, however, due to the close localisation of the filters, the risk of blocking of all filters is roughly of the same magnitude as in case of one filter. The risk of blocking the filter disclosed in U.S. Pat. No. 4,938,750 is relatively high due to the localisation of the filters aligned with the stoma receiving opening.
EP patent application No. 1 051 955 A2 discloses a bag for receiving discharge from the human body, said bag having a distal and a proximal wall one of which has a gas venting aperture and a filter for deodorising gas vented through the venting aperture wherein a filter package may be located at one or both sides of the bag wall. EP patent application No. 1 051 955 A2 does not disclose more filters having separate inlet openings communicating with the inner space of the bag.
U.S. Pat. No. 4,938,749 discloses a filter housing for mounting on an ostomy pouch, said housing having a base member having a central gas inlet passageway and three exit passageways radially offset from the inlet passageway and said housing further having a cover member having a recess with three connecting passageways which extend in a radial direction a distance from the central axis of the cover member greater than the distance between exit passageways and the axis of the base member, said base member being able to move between a first position in which said connecting channel aligns with said exit passageway and a second position at which said connecting channel is remote from said exit passageway. Thus, U.S. Pat. No. 4,938,749 does not disclose more filters having separate inlet openings communicating with the inner space of the bag.
However, it has been found that even when using such filters there is a risk, especially at night when ostomates turn in bed, of directly pressing faeces in the receiving bag against the inlet opening(s) of the filter and that the pressure may be sufficiently high to pass the viscerous material through a foam material covering the inlet opening of the vent and to cause a blocking of a microporous oleophobic covering the inlet opening of the vent.
Thus, there is still a need of measures for effectively preventing blocking of the inlet opening of filters of ostomy appliances.
It has now been found that it is possible to reduce the risk of blocking of the inlet opening of filters of ostomy appliances in a manner that almost eliminates the risk and, at the same time, is simple to carry out in industrial practice.
Thus, it has been found that the above drawbacks can be avoided by improving the geometry of the passage to the inlet opening of the filter.